Rectifier element and stack



Jan. 28, 1947. c. A. CLARKE 2,414,801

RECTIFIER `EI.`E}'\MEN'1 AND STACK Filed June 16, 1942 INVENTOR CARO/.f 'CLARKE A'TORN Patented Jan.- 28, 1947 REC'IllFIER ELEIWENT AND STACK Carole A. Clarke, Glen Ridge, N. J.,- assignor to Federal Telephone and Radio Corporation, a.

corporation of Delaware Application June it, 1942, serial No. 447,295

This invention relates to dry rectier stacksl and has for its object to provide a simple stack for such rectifers. l

The invention is applicable to rectifiers of the dry plate type. `An element of such a rectifier ordinari'y comprises a base plate coated with a semi-conductor layer such as selenium over which there is placed a counter-electrode layer which `12 claims. 11.175-366) in turn is covered by a metallic plate or electrode.

'a boss which) spaces the next adjacentv rectifier element in the stack. A contact member or plate may if desired be fitted over the boss to perform a cooling function and may be made to establish contact between adjacent rectifier elements in the stack.

The invention will be better understood from the following-detailed description when taken'in conjunction with the accompanying drawing of v which Fig. v1 is a face view of a base plate containing a coating of selenium, made in accordance with this invention;

Fig. 2 is a cross-section side view of the devicel 'in Fig. l;

Fig. 3 is a face view of a metallic contact member used in the stack;

Fig. 4 is a side view of the contact member of Fig. 3;

Fig. 5 is a cross-sectional view of a stack assembled according to this invention;

Fig. 61s a face view of a metallic cooling member which may be used in the stack; l

Fig. '7 illustrates an insulating collar which may be yused with the stack; and

Fig. 8 is a cross sectional view of an alternative form of stack according to this invention.

Referring to Figs. 1 and 2 of the drawing, the dry rectifier element may be made by a coating of selenium 4 placed on a base plate, preferably of steel I, in a well known manner. This is preferably` done by coating the surface o f plate I with nickel and roughening it so that the selenium will adhere, and then melting the selenium onto the roughened plate causing the selenium to fuse 2 to the plate. The plate I is formed into a boss 2 at its central location, as shown, and a hole 3 i`s provided through which the 'usual mandrelV is placed when the rectifier is stacked. The seleniumlayer 4 is coated on its outer surface with a metallic coating 5 which is preferably sprayed onto the selenium to make an intimate contact with it. The base p'atel constitutes one electrode or terminal of the rectifier element and the coating 5 constitutes the other terminal or counter-electrode ofthe rectier.

diameter as hole 3 in the rectifier plate.

A number of rectifier elements as shown in Figs. 1 and 2 may be stacked by placing between successive elements a contact member.. Such a contact member is shown in Figs. 3 and 4: wherein the contact disc 'l is a spring member ordinarily of brass provided with a raised central boss 8 through which there is a hole 9 of about the same A number of radial slots I0 serve to improve the resilience of the member 1 s'o that the portion around the boss 8 will flatten down as shown in Fig. 4.

4The assembly into a stack of a number of rectier elements according to my invention is illus# trated 'in Fig. 5, wherein the rectier plates of the type of Figs. 1 and 2 are interleaved with the the back of boss 2. The assembly may be mounty rectifier elements.

'ed in the usual manner upon a mandrelor bolt Il and clamped between end clamps which are.

not shown. The pressu-re on the clamp should be sufficient to ilatten the outer circumferential portion of members 1 against the counter-electrode surfaces 5, while allowing the bossesV 8 to remain raised to create a space I2 between the Any number of the rectifier elements and members 'l may be stacked up in series to form a rectier, the number depending upon. the circuits, voltages and currents with which the rectifier is to be used.

The use of a base plate I having a boss 2 according to this-invention has the advantage of away heat.

enabling the rectifier elements to be stacked without the necessity for any Washer` between adjacent elements. Such a washer has been necessary under the prior practice in which the base plate of the rectifier element had been made :as a flat plate or disc without any boss such as boss 2.

In accordance with another feature it is possible to use a cooling element; or disc to conduct in the nat disc I3, for example, has a centrally located hole Il of a diameter large enough to pass over the boss 2 and advantageously fits snugly over the boss to hold the disc in place.

Sucha disc is shown in Fig. 6 where- -.-.fwashers Il of Figure 8 may be placed in the f "spaces I and I8 within the bosses Z-and 8, re-

spectively. Othermeans, known to men skilled in the art "serving the same purpose can 'be provided as a bolt II of insulating material or a sleeve (not shown) of insulat material put over the bolt It. 1.

A possible alternative manner of stachng the elements which eliminate the spring contact member 'i whileutilizing the member I3 both as a cooling member and a contacting member is illustrated in Fig. 8. The thickness of member i3 is made equal to the elevation of boss Z so that v,the plate I3 just lits between the bach of base plate l and the counter-electrode 5 of the next adjacent element. This stack is shown with the insulating washers Il in position. It will be understood that in this arrangement the plates I3 need not necessarily be enlarged beyond the peripheries of the rectifier discs as shown in Fig. 8, but might be made of lsubstantially the same diameter or even of the somewhat smaller diameter of the counter-electrode layer 5. When enlarged as shown in Fig. 8, however, these plates perform the function of conducting heat away from the rectier as well as making contact between adjacent elements. y

The assembly arrangements according to my invention eliminate the use of any spacing wash-- ers together with the attendant work of asserm-` bling such additional elements.

l. In a .rectifier stack, a rectifier element comprising a base plate having a boss at a central portion, a semi-conductor layerl over one surface of the base plate, and a counter-electrode over the surface of the semi-conductor layer, and a contacting member over the counter-electrode and having a portion which abuts against the boss of the next succeeding base plate.

2. In a rectiiierstack, a rectifier element comprising a base plate having a boss at a central' portion, a semi-conductor layer over the surface opposite the boss, anda counter-electrode layer over the surface of the semi-conductor layer, a contactingmember having a flattened portion in contact with said counter-electrode layer and a raised boss portion projecting away from said semi-conductor layer and against the boss of the base plate of the next succeeding rectiiier element, and a cooling disc having an opening which ts over the boss of the'base plate and in contact with the back of the base plate.

5. Apparatus Aaccording to claim 4 in which said cooling member is held into position by the boss of the contacting'member.

6. In a rectler stack, a base plate, a selenium coating thereon, said base plate having an embossed portion having an opening through it', and a contacting plate adapted to be placed against the surface of the base plate which is opposite adapted 'to lt over the boss of the base plate.

7. Apparatus according to claim 6, in which l the second mentioned plate is of larger diameter than the base plate to act as a cooling element.

8. In a rectier stack, a base plate, a semi-conductor coating thereon, said base plate being formed with an embossed portion having an openingthrough it, a contacting plate adapted to be placed against the surface of the base plate which is opposite the semi-conductor coating and having an opening adapted to fit over the boss and an insulating lwasher which lits within the embossed portion and is of a thickness which causes it to fill the space between the inside of the embossed portion and the outside of the embossed portion of the next base plate in the stack. 9. A rectifier element comprising a base plate having a flat portion and a boss struck up therefrom, a mounting selenium coating on the side of and extending solely over said nat plate por-l tion which is opposite said boss, and a counterelectrode layer over said selenium layer.

10. A rectifier element comprising a base plate having a fiat portion and a centrally located embossed portion, a hole through said embossed portion, a selenium layer on the side of said at v*portion opposite the boss and a counter electrode over said selenium.

11. A rectifier stack comprising a plurality of rectier elements, each element comprising a base plate having a boss at a central portion, a semiconductor layer on the surface of the base plate 12. A rectifier lstack according to claim 11 in v which the contactingmember includes a raised portion engaging the boss of said next adjacent element.

CAROLE A. CLARm. 

